Bipolar digitizer having compression capability

Claim 1

Signal processing apparatus comprising: sample and hold means for sampling and temporarily storing discrete voltage segments of an applied analog signal waveform, said sample and hold means including a capacitor for temporarily storing said discrete voltage segments, ramp generator means for providing a linearly-rising ramp voltage waveform, signal inversion means connected to the output of said sample and hold means, single comparator means coupled to said sample and hold means and to said ramp generator means for initially determining the polarity of a stored voltage segment of said analog signal waveform and for thereafter providing an output indication when the magnitude of said ramp voltage waveform exceeds the absolute magnitude of said stored voltage segment, first switch means for initially connecting the output of said sample and hold means to a first input terminal of said comparator means, and for thereafter connecting the output of said signal inversion means to said first input terminal when the said stored voltage segment has a negative value, second switch means for initially connecting a ground reference potential to a second input terminal of said comparator means to determine the polarity of said stored voltage segment and for thereafter coupling said ramp voltage waveform to said second input terminal of said comparator means, and digital counting means responsive to the output of said comparator means for providing a digital pulse waveform representative of the time required for said ramp voltage to exceed the absolute magnitude of said stored voltage segment.